Device for generating and dispensing foam

ABSTRACT

The invention relates to a device for generating and metering foam, especially foamed soap. To prevent further dispensing of drips of residual foam in a foam outlet channel after the quantity required has been supplied, the device is constructed in such a way that the underpressure subsisting on the return stroke of a piston in an air chamber is effective in the foam outlet channel and sucks residual foam back.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an appliance for the generation and dischargeof foam, in particular soap foam.

2. Description of the Prior Art

Such appliances are installed at washing points of, for example, bathingestablishments and toilets, in order, for example for washing the hands,to generate and discharge a metered quantity of soap foam. A simpleactuation of the appliance by hand is sufficient for this purpose, inorder to generate and at the same time issue a specific quantity offoam. Appliances of this type can be part of a foam dispenser installedfixedly above or at the washing point or also be arranged as anattachment directly on a liquid storage tank.

U.S. Pat. No. 1,896,624 discloses a soap-foam dispenser which consistsof a housing having a cylindrical air chamber of variable volume and ofa device, arranged coaxially thereon, for conveying foamable liquid outof a tank simultaneously with the conveyance of air, the device beingformed from a plunger piston retractable into a suction-side sic! withnon-return valve by the actuating element for the compression of air,and both the air chamber and a chamber provided with the non-returnvalve being connected, in the device, to a foaming chamber, to which thefoam-outlet duct is connected. The housing part surrounding the airchamber serves at the same time as an actuating element for thecompression of air and for the conveyance of the air into the foamingchamber which is arranged in a part of the foam-outlet duct fixedlaterally to the housing. When a compression stroke for the air ends,the foam expulsion also ceases, that is to say formed foam remains bothin the foaming chamber and in the foam-outlet duct, runs out or becomesencrusted in the course of time, particularly when the appliance remainsunused for a relatively long time. No return suction of the foam occurs,because the air chamber does not acquire its thrust of air through thefoam-outlet duct, but through an orifice in the wall of the air chamber.

An attempt was made to solve this problem with a foam dispenseraccording to European Patent 0,019,582, in that, after the foamdischarge, residual foam remaining in the mixing chamber and in thefoam-outlet duct is blown out. However, this is at the expense of aspecial construction of the appliance which makes it possible first togenerate and expel foam and then subsequently to expel the residual foamwith a further air blast, this usually always entailing an "afterdrip"of foam. Apart from that, a special air-cushion chamber is necessary, sothat the liquid which has flowed in there from a storage tank can bedriven by means of a valve-slide piston into the foaming chamberarranged stationarily in the dispenser housing, whilst the slide pistonhas to be guided with an exact fit in a cylinder.

Proceeding from a foam dispenser according to U.S. Pat. No. 1,896,624,the object on which the present invention is based is to provide a foamdispenser which, whilst having a simple construction, makes thesubsequent blow-out unnecessary and prevents a possible afterdrip offoam or of foam which has become liquid again.

SUMMARY OF THE INVENTION

This object is achieved by means of an appliance according to thepresent invention having the following features:

the appliance consists of a housing having a cylindrical air chamber ofvariable volume and of a device, arranged coaxially thereon, forconveying foamable liquid out of a tank simultaneously with theconveyance of air, the device being formed from a plunger pistonretractable into a sic! on the suction side with non-return valve by theactuating element for the compression of air, and both the air chamberand a chamber provided with the non-return valve being connected, in thedevice, to a foaming chamber, to which the foam-outlet duct isconnected. At the same time, there is arranged in the air chamber apiston having a central insert which is fixedly connected to the piston.The unit formed from the insert and piston is supported against thebottom of the air chamber by means of a spring. Arranged in the insertis an air duct which connects the foaming chamber, arranged centrally inthe insert, to the air chamber. There projects into the insert in amanner directed towards the foaming chamber and fixedly connectedthereto the open end of the plunger piston which is provided with aconveying duct and which is displaceable in the device for theconveyance of liquid, and there is arranged in the air duct, upstream ofits entry into the foaming chamber, a foam return-suction valve whichconnects the air duct to the foam-outlet duct.

Apart from the fact that, in the foam dispenser according to theinvention, all the elements necessary for the supply of air and theformation of foam are concentrated in or on the actuating element forchanging the volume of the air chamber, specifically also thefoam-outlet duct, this foam dispenser utilizes the return stroke broughtabout positively by the spring, in order to cause the suction occurringthereby to take effect on the foam-outlet duct and to suck back residualfoam located therein. There is therefore neither a follow-up ejection offoam by blowing out, as in the foam dispenser according to EuropeanPatent 0,019,582, nor an afterdrip of foam or of foam which has becomeliquid again, this being possible in the foam dispenser according toU.S. Pat. No. 1,896,624.

The appliance according to the invention and advantageous embodimentsare explained in more detail below by means of the graphicalrepresentation of exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a section through a preferred embodiment of the appliance;

FIG. 2 shows the appliance according to FIG. 1 in a side view;

FIG. 3 shows the actuating element according to FIG. 1 separately and insection;

FIG. 4 shows, in section, another embodiment for direct arrangement on aliquid storage tank;

FIG. 5 shows the device for the conveyance of liquid separately and insection;

FIG. 6 shows, enlarged, a section through the actuating element for theconveyance of air and liquid and formation of foam according to FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As is evident from FIG. 1, the appliance according to the inventionconsists of a housing G having a cylindrical air chamber 1 of variablevolume and of a device 2, arranged coaxially thereon, for conveyingfoamable liquid out of a tank V simultaneously with the conveyance ofair, the device 2 (see also FIG. 5) being formed from a plunger piston 5retractable on the suction side with non-return valve 3 by the actuatingelement 4 for the compression of air, and both the air chamber 1 and achamber 6 provided with the non-return valve 3 being connected, in thedevice 2, to a foaming chamber 8, to which the foam-outlet duct 9 isconnected. Arranged in the air chamber 1 is a piston 10 having a centralinsert 11 which is fixedly connected to the piston 10. The unit formedfrom the insert 11 and piston 10 is supported against the bottom 13 ofthe air chamber 1 by means of a spring 12. Arranged in the insert 11 isan air duct 14 which connects the foaming chamber 8, arranged centrallyin the insert 11, to the air chamber 1. There projects into the insert11 in a manner directed towards the foaming chamber 8 and connectedfixedly thereto the open end 7 of the plunger piston 5 which is providedwith a conveying duct 5' and which is displaceable in the device 2 forthe conveyance of liquid, and, furthermore, there is arranged in the airduct 14, upstream of its entry 15 into the foaming chamber 8, a foamreturn-suction valve 16 which connects the air duct 14 to thefoam-outlet duct 9.

For reasons of simple production, the unit, which is formed from thepiston 10 and insert 11 and which constitutes as a whole the actuatingelement 4 for changing the volume of the air chamber 1, is formed from aplurality of parts which, however, are all fixedly connected to oneanother.

As shown separately in FIG. 3 for the sake of clarity, the sleeve-shapedinsert 11 forms one piece with the piston 10. The bottom 17 of theinsert 11 has orifices 14' and a sleeve 18 which extends on both sidesand of which the part 17' projecting into the air chamber 1 receives theopen end 7 of the plunger piston 5 and the inward-directed part 17" ofwhich forms the inner wall of a part 14" of the air duct 14, annularlycylindrical as a whole, which is limited, on the other hand, by afurther sleeve 19. This sleeve 19 contains orifices 20 for the air abovethe annular entry 15, the spaces 21 forming the foaming chamber 8,downstream of which is located towards the foam-outlet duct 9 a foamingelement 8'. Arranged above the sleeve 19 is a third sleeve 22 which islikewise seated fixedly in the insert 11. Arranged in the bottom 23 ofthis sleeve 22 are a plurality of orifices 24 which, together with anelastic ring 25, form the foam return-suction valves 16. Seated on theentire insert 11 is a cowl 26 which also contains the foam-outlet duct9, from which a suction bore 27 makes the suction connection with thefoam return-suction valves 16. This cowl 26 also has a recess 28 for apull clip 29 which is adjusted in the direction of the arrow P by a handlever 30 when the latter rotates in the direction of the arrow P' aboutits axis 31 on the housing 1. At the same time, the piston 10 is pressedinto the air chamber 1 and compresses the air which passes through theorifices 14' into the air-guide ducts 14, 14" and from there to theannular entry 15 into the space 21 (premixing chamber) where the airmeets the liquid to be foamed. When the entire unit consisting of thepiston 10 and insert 11 is pressed down, the plunger piston 5 (see FIG.5) fixedly connected thereto is also pressed into the chamber 6. Duringthe penetration of the plunger piston 5, transverse bores 5" leading tothe conveying duct 5' are exposed, and the liquid displaced by theplunger piston rises upwards in the conveying duct 5' into the foamingchamber 8. The foam formed in the latter then emerges at the end of thefoam-outlet duct 9 and is received there by the palm of the user's hand.As soon as the lever 30 is released, the unit consisting of the piston10, insert 11 and plunger piston 5 is reset again by means of the spring12. This resetting operation ensures that new liquid is sucked into thechamber 6 of the device 2 and that a vacuum is formed in the air chamber1 and opens the foam return-suction valves 16, so that the vacuum canalso take effect in the foam-outlet duct via the bore 27 and suck backthe residual foam located there into the cavities of the insert 11, thatis to say into the spacious part of the air duct 14, out of which thefoam or the possibly reformed liquid is then entrained by the air againwhen the next actuation occurs.

The appliance which is illustrated in FIGS. 4 and 6 and which isintended for direct attachment onto a liquid tank V' works on the sameprinciple. Corresponding parts of this embodiment bear correspondingreference symbols, so that there is no need to describe them again.

The housing G in the embodiment according to FIG. 1 is formed, here, bythe neck H of the liquid tank V', into which the air chamber 1 isscrewed. A stop 32 in the embodiment according to FIG. 1, which limitsthe stroke of the piston 10 together with its insert 11, is formed, inthe embodiment according to FIG. 4, by a stop ring 34 screwed onto thewall 33 of the air chamber 1.

As a comparison of FIGS. 1 and 5 in terms of the devices 2 shows, theseare largely identical, with the exception of slightly different detailsof construction. Here, as there, the plunger piston 5 slides in astationary sealing sleeve 35, and the non-return valve 3 also has aspring 36 which likewise participates in the resetting operation.

In the embodiment according to FIGS. 4 and 6, the air-inflow orifice 14'constitutes an annular gap, whereas, in the embodiment according toFIGS. 1 and 3, this is formed from a plurality of such orifices 14'which are arranged distributed on a semicircle 38, upper in relation tothe mid-axis 37, thus ensuring, in this embodiment, that foam which issucked back cannot pass into the air chamber 1.

Whereas, in the embodiment according to FIGS. 4 and 6, the air chamber 1together with the unit consisting of the piston 10 and insert 11 isseated directly in the neck H of the liquid tank V', in the embodimentaccording to FIG. 1 the liquid tank V is seated in a neck H of thehousing G which is provided with a ventilating valve 39 and in which, asshown, the device 2 having the air chamber 1 is arranged, that is tosay, in this case, the foamable liquid is sucked up out of the chamber40 of the housing G.

I claim:
 1. An apparatus for the generation and metered discharge offoam comprising:a housing having a cylindrical air chamber of variablesvolume; a device arranged coaxially on the housing for conveyingfoamable liquid out of a tank simultaneously with the conveyance of air,wherein the device comprises a plunger piston retractable on a suctionside of the device and defines a chamber receiving a non-return valvehaving an actuating element for the compression of air, wherein the airchamber and the chamber receiving the non-return valve are eachconnected to a foaming chamber; and a foam-outlet duct connected to thefoaming chamber, the device further comprising: a piston arranged in theair chamber, the piston having a central insert fixedly connected to thepiston, a unit formed from the central insert and the piston beingsupported against a bottom of the air chamber by a spring; an air ductarranged centrally in the central insert, the air duct being connectedto the air chamber; an open end of the plunger piston projecting intothe central insert towards the foaming chamber and fixedly connected tothe central insert, the plunger piston having a conveying duct and beingdisplaceable in the device for the conveyance of liquid; and a foamreturn-suction valve arranged in the air duct upstream of the foamingchamber, the foam return-suction valve connecting the air duct to thefoam-outlet duct.
 2. The device according to claim 1, wherein thecentral insert comprises a sleeve integrally formed with the piston,wherein a part of the sleeve projects into the air chamber and receivesthe open end of the plunger piston, the central insert furthercomprising a second sleeve for limiting a part of the air duct, whereinthe second sleeve defines an entry into the foaming chamber.
 3. Thedevice according to claim 2, including a third sleeve inserted in theinsert, the third sleeve having a bottom portion defining a plurality oforifices, wherein the orifices together with an elastic ring, form aplurality of foam return-suction valves.
 4. The device according toclaim 2, including a cowl arranged on the insert, the cowl defining thefoam-outlet duct and a bore, wherein the bore pneumatically connects thefoam-outlet duct to the foam return-suction valves.
 5. The deviceaccording to claim 4, wherein the cowl defines a recess for receiving apull clip, wherein the pull clip is coupled to a hand lever pivotablymounted on the housing.